Men's tennis has become a must-see sport due to Roger Federer and Rafael Nadal. But someday it'll need some fresh blood.

On Sunday, Roger Federer won his first French Open, tying Pete Sampras for Grand Slam victories (14) and becoming the sixth man to win all four slams in his career (he and Andre Agassi are the only ones to do so on three different surfaces). After the trophy ceremony, former tennis great and current NBC announcer John McEnroe was unequivocal in his analysis, calling the Swiss "the greatest of all time."

Federer didn't disagree, and neither did the fans. And, perhaps more importantly, Federer has plenty of top-flight playing years left in him. Even better for tennis: Nadal could become even greater than Federer one day.

Men's tennis has been slowly regaining some of the luster that was lost after the days of McEnroe, Bjorn Borg and Jimmy Connors, in large thanks to Federer and his arch rival, Nadal (who has a knee injury and may not play Wimbledon). They have made Grand Slam men's tennis a must-watch for sports fans.

On the flip side, women's tennis, without a dynasty or a select few dominant players, is in a slumber. The day before Federer made history, the women's final match saw Svetlana Kuznetsova defeat a nervous Dinara Safina; it was a match completely devoid of intrigue. The women's tour suffers from a seeming indifference of some of its stars (the Williams sisters) and injuries to others (Maria Sharapova).

While the men's tour has seen Federer and Nadal seamlessly take the handoff from the Sampras-Agassi duels of the '90s, the women's tour is in a holding pattern. Chris Evert and Martina Navratilova handed off to Steffi Graf and Monica Seles; then, eventually, came the Williams sisters. And their era of dominance may be over, with nobody ready to take the reigns.

Women's tennis needs a new player to step up now. On our recent list of the best players who have yet to win a Grand Slam event, Elena Dementieva finished on top. She was followed closely by Safina--who showed on Saturday that she's not ready to take the throne.

The men's side is not in imminent trouble, but someday it'll need new challengers as well. Our list of the best men's players yet to win a Grand Slam included players from Nikolay Davydenko to David Nalbandian, Fernando Gonzalez to Tommy Robredo, but none seem ready to challenge Federer or Nadal quite yet.

This is OK--for now. But eventually, someone will need to step up. The health of their sport depends on it.

Robredo #2 of tennis players not to win a slam?? In what world? Has he even made a slam semi? I'd put Nalbandian #1, #2 Davydenko, #3 Murray, #4 Ferrer, and #5 Haas. But that's just me. I don't see how Robredo's even on that list, considering he's never been mentioned as a legit contender at any slam in his career. #2? Come on.